Flexible printed circuits

ABSTRACT

Flexible printed circuits comprising copper circuitry electrolessly deposited on an activated ink coating prepared by heating a wet ink comprising a polymer, e.g. polyvinyl chloride or a butadiene polymer, and a Group 1B or 8 compound, e.g. palladium dichloride, which is adapted to drying at room temperature to a catalytically inert ink. Selective areas of the ink activated by application of heat or light, e.g. a laser, are catalytic to electroless deposition of copper.

This application is a division of Ser. No. 07/468,509, filed Jan. 22,1990 and issued as U.S. Pat. No. 5,075,037, which is a division of Ser.No. 07/320,914, filed Mar. 7, 1989 and issued as U.S. Pat. No.4,910,072, which is a continuation of Ser. No. 06/928,499, filed Nov. 7,1986, abandoned.

Disclosed herein are inventions relating to polymeric films hat can beactivated to provide catalytic surfaces, e.g. to catalyze electrolessdeposition of metals, to precursors of such film, to methods ofpreparing and using such films, to he activated films and to articlescoated with such films. Also disclosed are inventions relating tostable, e.g. oxidation resistant, coatings of electrolessly depositedmetals such as copper and to methods of providing such costings. Moreparticularly disclosed are inventions relating to such films and methodsbased on polyvinyl chloride (PVC) that can be activated to providecatalytic surfaces, e.g. to electroless deposition, over selective areasof the film surface.

BACKGROUND OF THE INVENTION

Catalytic surfaces are provided on polymer substrates for a variety ofpurposes, including to provide initiation for electroless deposition ofmetal. Electroless deposition as used herein refers to the surfacedeposition from solution of a reduced metal coating onto a substrate byuse of a chemical reducing agent without an outside source of electriccurrent. Electroless deposition is used to deposit such metals asnickel, copper, gold, rhodium and palladium onto non-conductivesubstrates, e.g. polymeric substrates, to provide printed circuitboards, laser or magnetic data storage devices, catalytic devices,electromagnetic shielding of electronic equipment housings, conductivecoatings, decorative coatings, antistatic coatings and the like.

Electroless deposition is generally catalyzed by reduced metal sites onthe surface to be coated. Such deposition is often initially catalyzedby reduced palladium compounds distributed over the surface. Onceinitiated electroless deposition is autocatalytic in that depositedreduced metal provides an expanding catalytic surface for furtherdeposition.

Considerable effort in the art of electroless deposition has beendevoted to improving the quality of electrolessly-deposited metalcoatings. U.S. Pat. No. 3,414,427 discloses that better adhesion ofmetal coatings is achieved by use of a more soluble complex, e.g. ofpalladium chloride, hydrogen chloride and water. Other developmentsbased on modified palladium complexes are disclosed in U.S. Pat. Nos.3,520,723 (cuprous iodide treatment), No. 3,847,648 (ketopalladiumcomplexes), No. 3,937,857 and No. 4,006,047 (thermodecomposablepalladium complexes) and No. 3,963,841 (dimethyl sulfoxide complexes).

Other attempts to improve metal coating adhesion have included etchingof polymeric substrates, e.g. with chromic and/or sulfuric acid. See,for instance, U.S. Pat. Nos. 3,370,974; 3,423,226; 3,437,507; 3,507,681;3,515,649; 3,616,296; and 3,702,286 which disclose various acid etchingtechniques which are often useful in preparing surfaces comprising ABS(a multiphase thermoplastic of dispersed butadiene with grafted styreneacrylonitrile copolymer).

Another method of improving adhesion is disclosed in U.S. Pat. No.3,488,166 where reducible catalytic salts are bonded to formaldehyderesin substrates.

The following list of treatments further exemplify a wide variety oftechniques disclosed in U.S. Patents for improving the quality ofelectroless deposition: (a) substrates of aromatic polyamines areprovided with hydroquinone radicals (No. 3,523,874), (b) polystyrenesurfaces are treated with ethoxylates (No. 3,533,828), (c) substrates ofcarboxylic acid polymers are treated with ammonia or alkylenimines (No.3,567,488 and No. 3,567,489, respectively), (d) PVC substrates aredehydrohalogenated and oxidized (No. 3,639,153), (e) polymeric surfacesare treated with quaternary amines (No. 3,684,572), (f) hydroxyfunctional filler is provided in polymer substrates (No. 3,701,675), (g)bipyridyls are incorporated into substrates (No. 3,853,589), (h)cyano-containing resins are incorporated into substrates (No.4,017,265), (i) substrates are treated hydrosols of compounds having atleast two oxygen atoms (No. 4,021,314); (j) substrates are pretreatedwith phosphorus compounds (No. 4,063,004), (k) substrates are subjectedto glow discharge (No. 4,250,225), and (1) discretecrystalline/amorphous regions are developed in polyphenylene sulfidesubstrates (No. 4,486,463).

In still other cases, e.g. as disclosed in U.S. Pat. Nos. 3,347,724;3,523,824 and 3,642,476, particles of reducible catalytic metalcompounds have been adhered to a surface by incorporating such compoundsinto a binder, such as a thermoplastic resin. See also U.S. Pat. No.3,560,257 where organic compounds of Group 1B and 8 metals are used witha variety of extenders (including polymers) to provide bonding betweenthe substrate and the catalytic organic compound. See also U.S. Pat. No.3,900,320 which discloses the use of thin polymer layers to provide areadily reducible catalytic metal salt on a substrate. Such layers areformed from polymer solutions where the weight ratio of polymer materialto catalytic metal compound is required to be substantially less thanabout 15 to 1.

Because of the high cost of preferred catalytic metals, e.g. palladium,an objective has been to find ways to utilize lower levels of catalyticmetal compound in combination with polymeric binders. In this regard,see U.S. Pat. No. 3,930,109 which discloses the application of thinfilms from dilute solutions or suspensions of polymeric binder andcatalytic compounds; useful films are prepared from polymer solutionscontaining as little as 0.4 percent palladium chloride based on theweight of the polymer component. See also U.S. Pat. No. 4,493,861 whichdiscloses the use of palladium complexes of (poly)butadiene fromsolutions with as low as 5.2 percent by weight of palladium (based onanhydrous polybutadiene). A disadvantage of such films is that theentire film surface is platable by electroless deposition. This meansadditional process steps are required when plating of less than theentire surface is desired, e.g. as in the production of printedcircuitry, selective decoration or selective shielding.

In this regard selectivity in surface coating by electroless depositionhas been provided in a variety of ways. For instance, U.S. Pat. No.3,615,471 discloses methods of making optical masks by coating atransparent plate (e.g. glass) with a transparent photoresist layercomprising, for instance, polyvinyl alcohol and a chromate salt togetherwith a plating catalyst. Such photoresist layer can be exposed to alight pattern and developed (e.g. solvent treated to remove theunexposed part of the layer) to leave a catalytic polymeric patternwhich can be electrolessly coated.

Other methods involve the use of photosensitive materials, e.g. topromote reduction of the catalyst metal (see U.S. Pat. No. 3,772,056) orto otherwise generate catalytic nuclei (see U.S. Pat. Nos. 3,719,49;3,779,785; 3,900,320; 3,925,578; 3,942,983; 3,959,547; 3,994,727; and4,560,643.) See also U.S. Pat. No. 3,672,986 which discloses theproduction of printed circuitry by electrolessly depositing a metalcoating over the entire surface of a board substrate. A patterned maskis applied to allow electroplating of the desired circuitry. The mask isremoved to allow chemical etching of the undesired portions of theoriginal electroless deposit. Other mask technigues are disclosed inU.S. Pat. No. 3,642,476. See also U.S. Pat. No. 3,656,952 whichdiscloses films containing palladium salts and photosensitive compoundsthat allow electroless deposition of photographic images.

Other technigues for electroless deposition over selected surfaces, e.g.for printed circuitry, are disclosed in U.S. Pat. No. 4,368,281 where aprecursor of the desired circuit is printed with a catalytic ink, e.g. asolution of resin, crosslinker, dye and high levels (5-15 by weight) ofpalladium complexes. See also U.S. Pat. No. 4,574,095 where vaporizedpalladium complexes are deposited as clusters on a laser-irradiatedpattern of polymer surface.

Since electroless deposition techniques generally involve a multitude ofsteps or somewhat sophisticated procedure which, as indicated above, mayinclude pretreatments, etchings, washings, masking, catalyst reductionand the like, there is still a need for simple, effective electrolessdeposition technology which can utilize low levels of expensive catalystcompounds with minimal waste.

In addition to the above-mentioned difficulties attendant withelectroless deposition processes it has been generally found thatelectrolessly deposited coatings of oxidation susceptible metals, e.g.copper, tend to rapidly discolor and lose their metallic appearance andproperties. Prevention of such oxidation is generally achieved byapplying a protective coating, for instance, of electrolessly depositedor electroplated nickel, electroplated copper, thermoplastic polymer orthermosetting resin.

OBJECTS OF THE INVENTION

An object of this invention is to provide polymeric films that can beactivated to provide catalytic surfaces, e.g. to initiate electrolessdeposition of metals. Such films are desirably activatable by simpletechniques, e.g. exposure to radiant energy. Such films should also beselectively activetable without the need to remove surfaces whereelectroless deposition is not desired or without the need for specialphotoreactive additives, such as photoactivatable crosslinkers orcatalyst reducing agents.

Another object is to provide polymeric films that are readily adherentlyapplied to a variety of substrates, e.g. filaments or rigid or flexiblesurfaces, and that are amenable to electroless deposition of metalswithout the difficulties of prior art practices such as etching,pretreatments and the like.

Still another object is to provide such polymeric films that are simpleand of low cost requiring low levels of normally expensive catalyticcompounds.

A further object of this invention is to provide substantiallysimplified methods of applying such selectively activetable surfaces toarticles.

Yet another object is to provide substantially simplified methods ofelecrolessly depositing metal on selective areas of a uniformly coatedsubstrate, e.g. extremely finely separated areas as required formicrocircuitry and data storage devices.

One more object is to provide electrolessly deposited copper coatingshaving substantially improved oxidation resistance. Other objects of theinvention include he provisions of methods for preparing and using suchfilms in electroless deposition of metals. These and other objects ofthe invention will be more readily apparent in the following detaileddescription.

SUMMARY OF THE INVENTION

It has been discovered that the foregoing objectives can be realizedwith films that are activatable, e.g. to electroless deposition ofcopper, where such films comprise complexes of polymers and compounds ofcertain metals selected from Group 1B or Group 8 (CATALYTIC METAL). Inmany embodiments, such objectives can be more advantageously realized byusing activatable films comprising PVC where the concentration ofCATALYTIC METAL is lower at the surface of the film than in the interiorof the film. In particular, it has been discovered that films consistingessentially of PVC and relatively low levels of palladium compounds canprovide surfaces that are selectively activatable to electrolessdeposition by the application of radiant energy, e.g. light or heat. Anespecially desirable aspect of this invention is that polymeric surfacescan be provided that are inert to electroless deposition except in thoseareas that have been activated, e.g. by light or heat. A furtherespecially advantageous and surprising aspect of this invention is thatcoatings of electrolessly deposited copper on such surfaces areexceptionally resistant to oxidation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 illustrate he effect of water on certain aspects of heinvention.

FIG. 3 illustrates the effect of metal concentration in severalembodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Throughout the specification, percentages of compositions are by weightand temperatures are in degrees Celsius, unless indicated otherwise.

The term "complex" as used herein refers to organo-metallic combinationswhere there is molecular interaction, e.g. pi bonding, between polymersused in the films of this invention and solubilized CATALYTIC METALcompounds, for instance such that there is no substantial phaseseparation between the organic and metallic moieties during filmformation.

As used in this specification and the appended claims, the term"substantially anhydrous" refers herein to materials useful in thevarious aspects of this invention that are essentially anhydrous orcontain water in such low proportion that performance properties are notmaterially different than when materials are essentially anhydrous, e.g.there is no substantial reduction in the degree of electrolessdeposition of metal on a film of such materials.

The term "catalytically inert" refers herein to polymeric films withnon-catalytic surfaces, e.g. surfaces onto which metal is noteffectively deposited from standard electroless plating solutions suchas disclosed in U.S. Pat. No. 3,329,512, incorporated herein byreference.

The term "activatable" refers herein to films of polymers complexed withCATALYTIC METAL that are substantially catalytically inert but which canbe made catalytic, e.g. receptive to effective deposition of metal suchas copper, nickel, cobalt and the like from standard electroless platingsolutions, by activation, e.g. of the surface, of the film. Suchactivation can be effected by radiant energy, e.g. ultraviolet (UV)light, laser beam, X-rays, electron beams, etc., and/or by heating thesurface, conductively or radiantly.

The term "activatably effective amount" refers herein to levels ofcomponents used in this invention, e.g. water, that permit activation offilms of this invention to the effective electroless deposition ofmetals. An "activatably effective amount" is to be contrasted with anamount of such component that substantially reduces or inhibits theactivation of the surface to electroless deposition. A particular aspectof this invention has been characterized in terms of activatablyeffective amounts of water, that is the amount of water that can beeffectively tolerated in solutions or films of this invention.

The term "oxidation resistance" refers herein to electrolessly depositedlayers of metals, in particular copper, that are substantially resistantto oxidation, as compared to electrolessly deposited metal coatingsprovided by prior art methods. In this regard, one aspect of thisinvention relates to electrolessly-deposited copper coatings that can beboth thin, e.g. typically not more than about 1 micrometer thick, andsurprisingly resistant to oxidation.

Polymers that can be useful in providing the complexes in the films ofthis invention include both saturated and unsaturated polymers.Unsaturated polymers, e.g. polybutadiene and polychloroprene, are oftenpreferred where the unsaturated bonds provide advantageous sites forcomplexes with the CATALYTIC METAL compounds. Other unsaturated polymersincluding polyacetylene, polydiacetylene, allylic polymers, unsaturatedrubbers such as polyisoprene and natural rubbers, certainethylenepropylene diene monomer rubbers, and copolymers of unsaturatedpolymers such as ABS, styrene butadiene rubbers and the like can also beemployed provided they form complexes with the CATALYTIC METAL compoundto form activatable films.

In other preferred embodiments the polymer is saturated and halogenated,e.g. polyvinyl halides. Especially preferred is polyvinyl chloride whichis believed, at least in some cases, to undergo dehydrohalogenation toform a complex with the CATALYTIC METAL compound.

Also expected to be useful in certain embodiments of this invention areother vinyl polymers such as polyvinyl alcohol, polyvinyl pyrrolidone,polyvinyl acetate, polyvinyl fluoride, polyvinylidene chloride and thelike; halogenated polyolefins such as chlorinated polyethylene;polyarylsulfones, polyphenylene ethers, polysulfides such aspolyphenylene sulfides; and copolymers and graft copolymers of suchsaturated and unsaturated polymers.

CATALYTIC METALS that have been found to be useful in combination withPVC to provide catalytically active sites for initiation of electrolessdeposition include gold, platinum, iridium, palladium, rhodium, andruthenium. It is believed that osmium, which has not been evaluatedbecause of its hazardous nature, and silver would also be useful forinitiation of electroless deposition. The other Group 8 and Group 1Bmetals, i.e. iron, cobalt, nickel and copper, have not been shown to beuseful in the films of this invention to initiate electroless depositionof copper onto activated films.

In many cases preferred CATALYTIC METALS are palladium and platinum. Ofthe two palladium is most often preferred. CATALYTIC METALS can beprovided with a variety of convenient ligands that have beendemonstrated as useful by practitioners in the art. Particularly usefulpalladium compounds include those where the ligands are nitrates,chlorides, nitriles such as acetonitrile, allylics or mixtures of suchligands or mixtures of compounds having such ligands. An oftenconvenient criterion in selecting the compounds useful in this inventionis solubility in the solvents used to provide precursor solutions forfilms. In this regard because palladium compounds are often of lowsolubility, it can be useful to enhance their solubility by providing asupplemental source of solubilizing ions such as chloride ions. Suchchloride ions can be provided from among the more soluble chloride saltssuch as lithium chloride or from hydrogen chloride, e.g. either gaseousor as muriatic acid (provided allowance for water content is made asdescribed below).

It has been found that the surface of films are advantageouslyactivatable when the polymer and CATALYTIC METAL compound are providedat a specific molar ratio based on the number of monomer units to thenumber of atoms of the CATALYTIC METAL (MONOMER/METAL RATIO). Moreparticularly, it has been surprisingly found that PVC films having aMONOMER/METAL RATIO of at least about 30 to 1 (and in some cases atleast about 20 to 1) can be activatable. For instance, in most caseswhere PVC is complexed with palladium compounds, films are activatablewhen the MONOMER/METAL RATIO is not less than about 30 to 1. In somecases, e.g. when such films are formed in low humidity environments, thefilms are activatable when the MONOMER/METAL RATIO is as low as about 20to 1, e.g. greater than about 15 to 1. That is, where certain films ofPVC complexed with palladium compounds are formed in low humidityenvironments and the MONOMER/METAL RATIO is less than about 20 to 1,e.g. about 15 to 1, the films are not catalytically inert but ratherwill, without surface activation, readily acquire a metal coating whenplaced in electroless plating solution. Where the polymer ispolybutadiene and the metal is palladium, films are activatable when theMONOMER/METAL RATIO is at least about 35 to 1.

More surprisingly, it has been found that such films are selectivelyactivatable. That is, selected portions of the surface of the film canbe made activatable while other portions of the film can beadvantageously maintained in a catalytically inert condition. Suchselective activation, e.g. to electroless deposition, is advantageouslyprovided by a number of methods that will be readily apparent to thoseskilled in the art such as by exposing selected areas of the surface toultraviolet light through a patterned mask.

As stated above, the concentration of CATALYTIC METAL compound isdesirably low such that non-activated films are catalytically inert.Such concentrations are a characteristic of the portions of the filmcomprising a complex of polymer and CATALYTIC METAL compound. In thisregard certain embodiments of this invention comprise films consistingessentially of such complex, e.g. of PVC and CATALYTIC METAL compound.In other embodiments films comprise portions of the complex in mixtureswith other polymers or multiphase films, e.g. films comprising distinctphases of complex and phases of other polymers, or block copolymers ofcomplex or even compatible blends of complex and other polymers. Toafford uniform electroless deposition on such polymer films it is inmany instances generally desired that the polymer phases comprisingcomplex be substantially uniformly dispersed, at least over the surfaceof the film.

In many cases where the polymer is PVC, it is often preferably desiredthat the PVC-containing portions of the film contain lower levels ofCATALYTIC METAL compound such that the MONOMER/METAL RATIO is at leastabout 60 to 1. To afford even more economical films it is in many casesdesirable to use even lower levels of CATALYTIC METAL, e.g. such thatthe MONOMER/METAL RATIO is at least about 90 to 1 or even higher. Forinstance, it has been found that effective metal coatings, depending onthe intended use of the plated article, can be achieved by electrolessdeposition onto PVC films where the MONOMER/METAL RATIO is even higher,e.g. as high as about 300 to 1 or even 700 to 1. In some instancessuitable electroless deposition can be achieved at MONOMER/METAL RATIOSof several thousand to 1, e.g. as low as about 6000 to 1. Thus it hasbeen surprisingly and advantageously found that polymeric films of thisinvention, e.g. consisting of PVC and palladium compounds, areselectively activatable, e.g. to electroless deposition, at extremelylow levels of CATALYTIC METAL, thus affording an extremely economicaluse of CATALYTIC METAL.

While not intending to be bound thereby it is believed that theoperability of this invention for PVC polymer is attributed to formationof pi-complexes of CATALYTIC METAL compounds with PVC. In this regard itis believed that at least certain CATALYTIC METALS can form pi-enylcomplexes with PVC that has been dehydrohalogenated. Accordingly,another aspect of this invention is directed to films comprising pi-enylcomplexes formed from PVC and a CATALYTIC METAL. It is further believedthat such pi-enyl complexes have the ability to migrate along polymerchains so that uniformly dispersed complexes generated within aselective area of the polymeric film can migrate to form substantiallyuniformly distributed clusters of such pi-enyl complexes especially atthe surface of the polymeric film. Such clusters which may comprise fromabout 3 to perhaps about 20 or more, e.g. up to about 150 or even 200,atoms of CATALYTIC METAL are believed readily amenable to reduction byreducing agents, such as formaldehyde, which are commonly found inelectroless plating solutions. Reduced CATALYTIC METAL at such clustersis then available to catalytically initiate electroless deposition ofmetal.

Support for such possible migration of pi-enyl complexes is believed tobe provided by surface analysis of films of PVC and palladium compoundsaccording to one embodiment of this invention. Prior to activation suchfilm surfaces exhibit negligible amounts of palladium metal, i.e. lessthan about 0.1 atom percent, while the concentration in the interior ofthe film contains as much as about 3 percent by weight of palladium.These films have been shown to be platably inert until surfaceactivation whereupon the films become active to electroless depositionand exhibit substantially increased levels of CATALYTIC METAL at thesurface. Accordingly, a further aspect of this invention comprises filmshaving pi-enyl complexes formed from PVC and a CATALYTIC METAL wheresuch films have an asymmetric distribution of such complex between thesurface of the film and the bulk of the film.

Another aspect of this invention is film-forming solutions which can beutilized to provide catalytically activatable film. Such film-formingsolutions can comprise polymer and a compound of a CATALYTIC METAL, bothof which can provide a functional complex as described above. Thesolvent for such solutions is not considered critical to this inventionand can comprise a number of organic solvents. Where the polymer is PVC,the solvent can comprise tetrahyrofuran (THF), methylene chloride,cyclohexanone, dimethyl acetamide, and the like, or a mixture ofsolvents for PVC with solvents for CATALYTIC METAL compounds. In thisregard THF has been found to be a particularly useful solvent. Suchfilm-forming solutions can comprise from about 1 to about 40 percentpolymer. The level of polymer may be adjusted to film-formingconditions, for instance higher levels of polymer may provide highersolution viscosities that may be desirable in forming films on sloped orvertical surfaces from which thinner solutions may flow. It is expectedthat those skilled in the art will be able to readily adjust processvariables such as the level of polymer, solution and/or film-formingtemperatures, etc., to provide appropriate films on desired surfaces.While the level of polymer is not considered critical, it has beenfound, where the polymer is PVC, that activatable films areadvantageously prepared from solutions comprising from about 5 to about15 percent PVC. What is critical to the solutions of this invention isthe relative proportion of polymer to CATALYTIC METAL. Such proportionis conveniently stated in terms of the above-described MONOMER/METALRATIO. The film-forming solutions of the invention can be cast ontosubstrate as thin films from which the solvent is evaporated into anenvironment to provide a residual film of PVC and CATALYTIC METALcompound.

In one aspect of this invention, films are substantially anhydrous beingformed from substantially anhydrous film-forming solutions in asubstantially anhydrous environment.

In another aspect of this invention, films comprise an activatablyeffective amount of water. For instance where the polymer is PVC, it hasbeen found that the presence of certain amounts of water in theprecursor film-forming solutions adversely affect the ability of theresulting films to be activatable, e.g. to electroless deposition. Ithas also been found that the presence of certain amounts of water in theenvironment in which films are prepared can also adversely affect theability of certain films to be activatable, e.g. to electrolessdeposition. In this regard reference is made to FIGS. 1 and 2 whichillustrate such effects of water in films comprising PVC and palladium,where such utility is characterized in terms of "percent plating" whichindicates the portion of a film surface area that became coated with ametal in an electroless plating solution. The water-based variables are"bulk water concentration" which is the percentage of water in thesolvent of the film-forming solution and "relative humidity" of theenvironment into which solvent is evaporated from a casting offilm-forming solution. The film-forming solution comprised about 10percent PVC and palladium at a MONOMER/METAL RATIO of about 60 to 1; theorganic solvent was THF. Other details are presented in Example 10below.

What FIG. 1 illustrates is that water can be tolerated in certainfilm-forming solutions provided the solution is formed into a film in anenvironment having a sufficiently high level of water, as indicated byrelative humidity. Also illustrated is that platable films can be formedin environments having a wider range relative humidity from solutionswhere the solvent contains higher levels of water, e.g. about 5-8percent, than where the solvent contains lower amounts of water, e.gabout 0-2 percent. This latter effect is also illustrated in FIG. 2.These figures illustrate more preferred aspects of this invention forfilms based on PVC and palladium. For instance, where it is difficult toeliminate ubiquitous water from film-forming solutions or from theenvironment in which films are formed, it is often desirable that, whenthe film-forming solution comprises THF solvent, the solvent comprisesabout 6 percent water, especially when it is difficult to control therelative humidity of the film-forming environment. In other cases,especially where it is difficult to control the amount of water in thesolvent, it is often desirable to prepare the films of this invention inan environment where the relative humidity is at least about 20 percent,more preferably at least about 30 percent or higher. An upper level ofrelative humidity is believed to be about 80 percent. In this regard ithas been found that films formed in an environment of about 85 percentrelative humidity have exhibited no selectivity toward activation. Thatis, such films were readily covered with a metal coating when depositedin an electroless plating solution without activation.

PREPARATION OF FILM-FORMING SOLUTIONS

Solutions for forming activatable films can be provided by methodssimilar to those described below where the polymer is PVC. Solutions ofPVC and CATALYTIC METAL can be prepared by dissolving PVC and CATALYTICMETAL compound in a common solvent. Generally such solutions have beenconveniently prepared by adding prepared solutions of the CATALYTICMETAL to prepared solutions of PVC. It is often convenient, but notnecessary that both prepared solutions comprise the same solvent, e.g.THF. In other cases, it may be preferable to dissolve the CATALYTICALMETAL compound (many of which are of low solubility) in another solvent.

With palladium compounds, other useful solvents include acetone, methylethyl ketone, methanol, methyl acetate and ethyl acetate. It is expectedthat other solvents, including mixtures, can be readily determined byroutine experimentation. In some cases, e.g. with compounds of lowsolubility, it may be useful to add soluble anions to the solvents toassist in dissolution. For instance, with palladium compounds, e.g.Pd(NO₃)₂ or PdCl₂ (CH₃ CN)₂, it has proven useful to add solublechloride salts, e.g. lithium chloride (LiCl), or acidic chloride, e.g.muriatic acid, to facilitate solubility. In other cases, where anhydroussolutions are not required, water can be used to facilitate solution oreven be a major solvent component for the CATALYTIC METAL compound.Although solvent temperatures have been kept low, e.g. generally aboutroom temperature, higher temperature may be useful in expediting thesolution of some compounds.

Useful solvents for PVC include THF, methylene chloride, andcyclohexanone. When water is desired in the film-forming solutions, itis, of course, advantageous to use a solvent which is miscible withwater at least up to the desired concentration of water, e.g. up toabout 8% in the solvent. Since PVC is a major film component, it isgenerally advantageous to prepare the PVC solutions in concentrationssuitable for the intended use. Generally such solutions will be at leastabout 1% PVC and no higher than about 40% PVC. A convenientconcentration will generally be between about 5% and about 20%. When PVCis dissolved in THF, solutions between about 7% and 15% PVC (e.g. about10% PVC) often have useful properties, e.g. in terms of viscosity,adhesiveness to substrates and film-forming speed.

FORMING ACTIVATABLE FILMS

The film-forming solutions can be used to provide activatable films in avariety of ways. As indicated in the following examples self-supportingfilms can be formed by casting the film-forming solutions onnon-adhesive supports. When sufficient solvent has been removed from thesolutions, a self-supporting film can be removed from the support.Depending on the film-forming conditions, e.g. MONOMER/METAL RATIO,amount of water in the solution, relative humidity in the environment,etc., such films can be activatable on either or both surfaces.

Articles can be provided with an activatable surface by coating thearticle with a film-forming solution of appropriate viscosity to assistin maintaining the desired film thickness. Coating can be effected byspraying, dipping and other procedures practiced in the coatingsindustry. For instance, filaments can be conveniently run through a bathof film-forming solution and printed circuits can be provided by usingthe film-forming solutions of this invention as inks to print aprecursor film to the desired circuitry. Alternatively, printed circuitscan be provided by coating a substrate, e.g. flexible film or rigidlaminate, with a film-forming solution to provide a film that can beselectively activated in those areas where circuitry is desired. Morespecifically, printed circuit board laminates can be advantageouslyprovided with circuitry, e.g. of electrolessly deposited copper, byselectively exposing an activatable coating to focused light, followedby immersion in an electroless plating solution. Extremely finecircuitry can be provided by surface activation with a laser ofcontrolled, narrow width.

With some substrates, e.g. ABS surfaces, extremely thin coatings can beachieved by providing a coating with a film-forming solution of PVC andpalladium and mechanically delaminating the bulk of the solid film,leaving a residue, e.g. of PVC complexed with CATALYTIC METAL, that isactivatable, e.g. to electroless deposition.

Another method of providing activatable surfaces on molded articlescomprises applying a film-forming solution to a mold surfacecorresponding to the desired activatable surface. When the solution issolidified to form a film, the pre-coated mold can be used to form thearticle. For instance, thermoplastic material cast or injected into themold will acquire a surface of the precoated film that can beselectively activated to electroless deposition. In some cases themolding temperatures or temperatures of molten thermoplastic materialmay be sufficient to activate the transferred surface. Such proceduresare useful for providing activated surfaces on the inside surfaces ofhousings for electronic components, e.g. to provide metal coatings byelectroless deposition for shielding against electromagneticinterference.

ACTIVATION OF FILMS

Activated films of this invention, including activated coatings, can beprovided by applying energy to the activatable films. In the case of PVCcomplexes with palladium, irradiation, e.g. U.V. radiation, or heatingcan be useful methods of applying energy for activation. In other cases,e.g. with complexes of polybutadiene or polychloroprene, irradiationrather than heating has been shown to be a useful method of activation.The type of activation selected may depend on factors such as thepolymer complex of the film, the topography of the film, the desiredcatalytic function and the desired selectivity of activation. Forinstance, it may be advantageous to heat filaments coated with anactivatable film to provide a generally activated surface as a precursorto a metal coated filament. In the case of providing electrolessdeposition of metal on data storage devices, e.g. laser readablesubstrates or magnetic readable substrates, it is expected to beadvantageous to selectively activate discrete areas with finely focusedradiation.

The following disclosure is provided to illustrate specific embodimentsand aspects of the invention but does not imply any limitation of thescope o f the invention.

EXAMPLE 1

The purpose of this example is to illustrate embodiments of thefollowing aspects of this invention: the preparation of a film-formingsolution comprising PVC and a CATALYTIC METAL compound, the preparationof activatable films from such solution, and the effects of surfaceactivation of such films.

10 g of PVC powder (Geon® 121 by B. F. Goodrich), dried in an oven at60° for 48 hours, was dissolved under an anhydrous nitrogen atmospherein 90 grams of dry THF to provide a dry 10% PVC solution.

Palladium dichloride bisacetonitrile (PdCl₂ BAN) was dried for 48 hoursat room temperature under a reduced pressure of about 21 millitort. LiClwas dried in an oven at 150° for 48 hours. Under an anhydrous nitrogenatmosphere 0.25 g of dry PdCl₂ BAN and 0.04 g LiCl were dissolved in1.36 g dry THF to provide a 6% Pd solution (about 15% PdCl₂ BAN).

An anhydrous film-forming-solution was prepared by combining 0.5 g ofthe 15% solution of PdCl₂ BAN and 10 g of dry 10% PVC solution toprovide a film-forming solution containing about 3% Pd and having aMONOMER/METAL RATIO of about 60 to 1.

The film-forming solution was cast and dried (e.g. solvent evaporated)into films of about 0.01 mm thickness on three glass slides under eachof the following three conditions: (a) in a substantially anhydrousnitrogen atmosphere, (b) in a nitrogen atmosphere containing water atabout 10% RH and (c) in a nitrogen atmosphere containing water at about85% RH. One set of three films (comprising one film prepared under eachof the three conditions) was not subjected to activation. A secondsimilar set of three films was activated by exposure to heat in a 180°oven for 5 minutes. A third similar set of three films, was activated byexposure to U.V. light for about 2 hours (film held about 25 mm from a254 nanometer wavelength mercury arc lamp receiving radiation about 7.5milliwatts/square centimeter).

Each film was stripped from the glass and immersed for about 5 minutesin a copper electroless plating solution prepared from copper sulfatepentahydrate, Rochelle salt (i.e. potassium sodium tartrate), formalin(i.e. 37formaldehyde), sodium hydroxide (50), andethylenediaminetetraacetic acid (EDTA) to provide a solution (CopperBath) of the following analysis:

    ______________________________________                                                  2.5  g/l copper                                                               3    g/l formalin                                                             6    g/l hydroxide ion                                                        22   g/l EDTA                                                                 pH   11.5-12.5                                                      ______________________________________                                    

The Copper Bath was maintained at about 38° and agitated by a magneticstir bar.

The results of the plating are found in Table 1 where the plating on theglass side of the film is in parentheses. The following symbolsqualitatively indicate the degree of film coverage by a copper coating:

0 (none)

=(very little)

-(little)

+(substantial)

++(total)

                  TABLE 1                                                         ______________________________________                                        ELECTROLESS DEPOSITION OF COPPER                                              ON PVC FILMS                                                                  ______________________________________                                        CATALYTIC METAL SALT: PdCl.sub.2 BAN                                          SOLVENT:              DRY THF                                                 CHLORIDE SOURCE:      LiCl                                                           Film-Forming Environment                                               Activation                                                                             Anhydrous   10% RH      85% RH                                       ______________________________________                                        None     0       (0)     0     (0)   =     (0)                                Heat     +       (+)     ++    (+)   ++    (-)                                U.V.     ++      (+)     ++    (0)   -     (-)                                ______________________________________                                    

EXAMPLE 2

In the manner of Example 1, this example serves to illustrate similaraspects of this invention where the CATALYTIC METAL compound ispalladium dichloride (PdCl₂). The procedures of Example 1 are repeatedexcept that 0.17 g of PdCl₂ is used to prepare the 6% Pd solution.

The results of the electroless deposition are found in Table 2.

                  TABLE 2                                                         ______________________________________                                        ELECTROLESS DEPOSITION OF COPPER                                              ON PVC FILMS                                                                  ______________________________________                                        CATALYTIC METAL SALT: PdCl.sub.2                                              SOLVENT:              DRY THF                                                 CHLORIDE SOURCE:      LiCl                                                           Film-Forming Environment                                               Activation                                                                             Anyhydrous  10% RH      85% RH                                       ______________________________________                                        None     0               0           =                                        Heat     +       (+)     ++    (+)   ++    (-)                                U.V.     ++      (+)     ++    (0)   -     (-)                                ______________________________________                                    

EXAMPLE 3

In the manner of Example 1, this example serves to illustrate similaraspects of this invention except where the CATALYTIC METAL compound ispalladium nitrate (Pd(NO₃)₂). The procedures of Example 1 are repeatedexcept that 0.22 g of Pd(NO₃)₂ is used to prepare the 6% Pd solution.The results of the electroless deposition are found in Table 3.

                  TABLE 3                                                         ______________________________________                                        ELECTROLESS DEPOSITION OF COPPER                                              ON PVC FILMS                                                                  ______________________________________                                        CATALYTIC METAL SALT: Pd(NO.sub.3).sub.2                                      SOLVENT:              DRY THF                                                 CHLORIDE SOURCE:      LiCl                                                           Film-Forming Environment                                               Activation                                                                             Anhydrous   10% RH      85% RH                                       ______________________________________                                        None     0               0           =                                        Heat     0       (+)     ++    (+)   ++    (-)                                U.V.     =       (0)     -     (+)   0     (0)                                ______________________________________                                    

EXAMPLE 4

In the manner of Examples 1, 2 and 3, this example serves to illustratethe distinct aspects of similar embodiments of this invention wheremuriatic acid is used instead of LiCl to assist in dissolution of thepalladium compound. The procedures of Examples 1, 2 and 3 are repeatedexcept that 0.09 g of 37% HCl is used in place of 0.04 g LiCl. Theresults are shown in Table 4.

EXAMPLE 5

In the manner of Examples 1, 2 and 3, this example serves to illustratethe distinct aspects of similar embodiments of this invention where anactivatably effective amount of water is incorporated into the solvent.The procedures of Examples 1, 2 and 3 are repeated except that thesolvent comprises 6% water in THF. The results are shown in Table 5.

                  TABLE 4                                                         ______________________________________                                        ELECTROLESS DEPOSITION OF COPPER                                              ON PVC FILMS                                                                         Film-Forming Environment                                               Activation                                                                             Anhydrous   10% RH      85% RH                                       ______________________________________                                        Catalytic Metal Salt: PdCl.sub.2 BAN                                          None     0               0           ++                                       Heat     =       (+)     0     (+)   -     (-)                                U.V.     ++      (-)     ++    (-)   -     (0)                                Catalytic Metal Compound: PdCl.sub.2                                          None     0               0           +                                        Heat     =       (+)     0     (-)   -     (-)                                U.V.     ++      (-)     ++    (-)   =     (0)                                Catalytic Metal Salt: Pd(NO.sub.3).sub.2                                      None     0               0           +                                        Heat     ++      (0)     0     (+)   ++    (-)                                U.V.     ++      (-)     ++    (-)   -     (=)                                ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        ELECTROLESS DEPOSITION OF COPPER                                              ON PVC FILMS                                                                         Film-Forming Environment                                               Activation                                                                             Anhydrous   10% RH       85% RH                                      ______________________________________                                        Catalytic Metal: PdCl.sub.2 BAN                                               None     0               0            =                                       Heat     ++      (+)     ++    (+)    =    (-)                                U.V.     ++      (0)     =     (0)    -    (-)                                Catalytic Metal: PdCl.sub.2                                                   None     0               =            =                                       Heat     ++      (+)     ++    (+)    -    (-)                                U.V.     ++      (0)     =     (0)    =    (-)                                Catalytic Metal: Pd(NO.sub.3).sub.2                                           None     0               +                                                    Heat     0       (+)     ++    (++)                                           U.V.     0       (0)     =     (0)                                            ______________________________________                                    

EXAMPLE 6

This example serves to illustrate that aspect of this invention where afilm can be stripped from a substrate to provide a substantially thinnerresidual layer that is activatable.

The film-forming solution of Example 3 was cast onto a sheet of ABS inan anhydrous nitrogen environment. The bulk of the film based on PVC andPd(NO₃)₂ was readily stripped from the ABS sheet. The ABS sheet was thenirradiated by U.V. light for about 18 hours and immersed in a CopperBath. A uniform copper coating was deposited on the surface of the ABSsheet from which the film had been stripped.

EXAMPLE 7

This example serves to illustrate that gold, a Group 1B metal, is usefulin embodiments of this invention. A film-forming solution was preparedessentially as in Example 1 except that HAuCl₄.nH₂ O was used as theCATALYTIC METAL compound to provide a solution having a MONOMER/METALratio of about 20:1. Films were prepared on glass slides in a nitrogenenvironment at 64% RH. Films were either (a) not activated, (b)activated by heat (180° for 5 minutes) or (c) activated by light (U.V.exposure for 24 hours) prior to immersion in a Copper Bath for 3minutes. A copper coating was deposited only on the activated films.

EXAMPLE 8

This example serves to illustrate that ruthenium, rhodium, iridium andplatinum (Group 8 metals) are useful in embodiments of this invention.Film-forming solutions were prepared essentially as in Example 1 usingeach of the following as CATALYTIC METAL compounds: PtCl₂ (CH₃ CN)₂,RhCl₃.nH₂ O, H₂ PtCl₆.nH₂ O, RuCl₃.nH₂ O, H₂ IrCl₆.nH₂ O, IrCl₃.nH₂ O,and PdCl₂ BAN where the MONOMER/METAL ratio was about 20: 1.

Films were prepared on glass slides under a nitrogen environment at 64%RH. Without further activation the films based on H₂ PtCl₆.nH₂ O andPdCl₂ (CH₂ CN)₂ were active to electroless deposition from a CopperBath. The other films, even when activated by heat (180° for 5 minutes)or light (U.V. for 24 hours) did not become copper coated to any visibleextent.

Additional films were prepared on glass slides under a nitrogenenvironment at about 3% RH. After activation by light (U.V. for 24hours) both platinum-based films exhibited some copper coating afterimmersion in a Copper Bath. After activation heat (180° for 5 minutes)and immersion in a Copper Bath, a metal coating was visible on therhodium, platinum, ruthenium, iridium and palladium based films.

EXAMPLE 9

This example serves to illustrate the concept of an activatablyeffective amount of water in embodiments of this invention.

Film-forming solutions were prepared essentially as in Example 1 exceptthat water was added to individual volumes of the solution to providethe solutions indicated in Table 6 where water concentration is based onthe weight of THF solvent and water.

Films were cast onto glass slides using film-forming solutions innitrogen film-forming environments having water ranging from 0-60% RH asindicated in Table 6. The films were activated by heat (180° for 5minutes) and then immersed in a Copper Bath. The effects of watercontent in the solvent and in the film-forming environment werequantified by projecting photographic slides of each film onto graphpaper. The percent plating, determined by the ratio of the projectedarea having a copper coating to the projected area of the entire PVCfilm, is indicated in Table 6.

Portions of the results are also graphically presented in FIGS. 1 and 2.

                                      TABLE 6                                     __________________________________________________________________________    COPPER COATING OF PVC FILMS                                                   PERCENT OF FILM AREA COATED                                                   Solvent                                                                       % H.sub.2 O                                                                        Film-Forming Environment, % RH in Nitrogen                               0    0 5 10                                                                              15                                                                              20 25                                                                              30                                                                              35 40 45                                                                              50 55 60                                          __________________________________________________________________________     0   35                                                                              0 40                                                                              11                                                                              0  0 0 0  0  0 60 67 83                                          0.1  14                                                                              --                                                                              2.6                                                                             --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 75                                          0.5  12                                                                              --                                                                              --                                                                              --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 75                                          1    0 0 3.2                                                                             0 0  0 0 0  0  0 60 76 82                                          1.2  0 --                                                                              15                                                                              --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 88                                          1.4  0 --                                                                              0 --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 77                                          1.6  0 --                                                                              0 --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 100                                         1.8  0 --                                                                              0 --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 100                                         2.0  0 0 2.1                                                                             0 0  0 0 0  31 17                                                                              29 70 100                                         2.5  0 --                                                                              0 --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 100                                         3.0  0 --                                                                              0 --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 100                                         3.5  0 --                                                                              0 --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 100                                         4.0  0 0 0 0 0  2.5                                                                             35                                                                              64 68 90                                                                              87 100                                                                              95                                          4.5  0 --                                                                              0 --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 95                                          5.0  0 --                                                                              0 --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 95                                          5.5  0 --                                                                              0 --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 95                                          6.0  0 0 0 29                                                                              85 87                                                                              94                                                                              93 100                                                                              89                                                                              89 63 100                                         6.5  0 --                                                                              0 --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 95                                          7.0  0 --                                                                              0 --                                                                              -- --                                                                              --                                                                              -- -- --                                                                              -- -- 100                                         8.0  0 0 0 7.3                                                                             22 58                                                                              62                                                                              46 56 77                                                                              59 26 79                                          __________________________________________________________________________

EXAMPLE 10

This example serves to illustrate the wide range of MONOMER/ME AL RATIOthat can be utilized in embodiments of this invention.

Separate volumes of film-forming solution, with MONOMER/METAL RATIO asindicated in Table 7, were prepared by mixing the 10% PVC solution ofExample 1 with THF dilutions of the 6% Pd solution of Example 1. Filmswere cast onto glass slides from each solution under nitrogenenvironments of 0, 10 and 60% RH, activated by heat (180° for 5 min.)and immersed in a Copper Bath. Percent plating, determined as in Example9, is reported in Table 7.

A semi-log plot of the results, FIG. 3, indicates that plating can beachieved at MONOMER/METAL RATIOS of less than about 5400 to 1.

                  TABLE 7                                                         ______________________________________                                        COPPER COATING OF PVC FILMS                                                   PERCENT OF FILM AREA COATED                                                              FILM FORMING ENVIRONMENT,                                          MONOMER    % RH IN NITROGEN                                                   METAL      0             10     60                                            ______________________________________                                         54        100           72     --                                             108       43            8.3    18                                             540       2             0      7.8                                           1080       13            5.1    1.5                                           5400       0             0      0                                             ______________________________________                                    

EXAMPLE 11

This example serves to illustrate the significance of MONOMER/METALRATIO in distinguishing activatable films of polymer complexed withCATALYTIC METAL from films that are not activatable.

10% PVC solution and 6% Pd solution, prepared essentially as Example 1,were combined to provide four film forming solutions havingMONOMER/METAL RATIOS of 15 to 1, 20 to 1, 25 to 1 and 30 to 1. Eachsolution was used to prepare films in nitrogen environments at lowhumidity (about 10% RH). For each solution, films were either (a) notactivated, (b) activated by light (U.V. for 21/2 hours), or (c)activated by heat (180° for 5 minutes) prior to immersion in a CopperBath.

A visual estimate of percent plating (based on film area) shown in Table8 indicates that for films of complexes of PVC and palladium, aMONOMER/METAL RATIO of greater than about 15 to 1 is required foractivatable films.

                  TABLE 8                                                         ______________________________________                                        PERCENT PLATING OF                                                            ELECTROLESSLY-DEPOSITED COPPER                                                Time                                                                          in             MONOMER/METAL RATIO                                            Activation                                                                            Bath       15:1   20:1   25:1  30:1                                   ______________________________________                                        None    2 min.     100    <2     0     0                                      U.V.    2 min.     100     90    0     5                                      Heat    1/2 min.   100    100    100   100                                    ______________________________________                                    

EXAMPLE 12

The example serves to illustrate embodiments of the following aspects ofthis invention: the preparation of film-forming solutions ofpolybutadiene and a CATALYTIC METAL compound, the preparation ofactivatable films from such solutions, the activation of such films, andthe electroless deposition of copper onto such activated films.

5 g of polybutadiene rubber (Diene 55™ by Firestone, Mw: 240,000; Mn:105,000)was broken into small particles and dissolved in 70 g of THF toprovide a 6.7% polybutadiene solution.

The polybutadiene solution was mixed with a 6% Pd solution (preparedessentially as in Example 1) in various proportions to provide solutionsof each of the MONOMER/METAL RATIOS indicated in Table 9. Each of thesolutions was cast into thin films on glass slides in nitrogenenvironments at room temperature both at high humidity (about 60-80% RH)and at low humidity (about 10% RH).

As indicated in Table 9 films prepared from each solution at each of thefilm-forming conditions were either (a) not activated, (b) activated byheat (180° for 5 minutes), (c) activated by light (U.V. for 2 hours asindicated in Example 1), or (d) activated by light (U.V. for about 24hours), prior to immersion in a Copper Bath for about 2 minutes.

A visual estimate of percent plating (based on film area) shown in Table9 indicates that for films of complexes of polybutadiene and palladium,a MONOMER/METAL RATIO of at least about 35 to 1 (in some cases at leastabout 40 to 1 or higher, say about 50 to 1) is required for activatablefilms.

                  TABLE 9                                                         ______________________________________                                        PERCENT PLATING OF                                                            ELECTROLESSLY-DEPOSITED COPPER                                                Monomer/Metal Ratio                                                           Activation                                                                            20:1    25:1   30:1  35:1 40:1  45:1 50:1                             ______________________________________                                        (a) Film formed at high humidity (62-80% RH)                                  None    100     100     95   80    30    20  10                               U.V.    100     100    100   100  100   100  100                              (21/2 hours)                                                                  Heat    100     100     95   25    30    0    0                               (b) Film formed at low humidity (about 10% RH)                                None    100      75     60   30   <1     0    5                               U.V.    100     100    100   85    60   <5   25                               (21/2 hours)                                                                  U.V.    100     100    100   100  100   100  90                               (24 hours)                                                                    ______________________________________                                    

EXAMPLE 13

This example serves to illustrate embodiments of the following aspectsof this invention: the preparation of film-forming solutions ofpolychloroprene and a CATALYTIC METAL compound, the preparation ofactivatable films from such solutions, the activation of such films andthe electroless deposition of copper onto such activated films.

5 g of polychloroprene rubber (from Aldrich Chemical Company, 10% cisisomer) was broken into small particles and dissolved in 65 g of THF toprovide a 7.1% polychloroprene solution.

1 part of a 6% Pd solution, prepared essentially as in Example 1, wasadded to 20 parts of the 7.1% polychloroprene solution to provide afilm-forming solution having a MONOMER/METAL RATIO of about 2 8 to 1.

As indicated in Table 10 films were cast on glass slides in nitrogenenvironments at room temperature both at a low humidity (about 8% RH)and at a high humidity (about 60% RH); such films were either (a) notactivated, (b) activated by heat (180° for 5 minutes) or (c) activatedby U.V. light (about 10 hours), prior to immersion in a Copper Bath.

A visual estimate of percent plating (based on film area) shown in Table10 indicates that such films of complexes of polychloroprene andpalladium are activatable.

                  TABLE 10                                                        ______________________________________                                        PERCENT PLATING OF                                                            ELECTROLESSLY-DEPOSITED COPPER                                                             Film-Forming                                                                  Environment, Nitrogen                                            Activation     8% RH    60% RH                                                ______________________________________                                        None           <2       0                                                     Heat            0       0                                                     U.V.           90       95                                                    ______________________________________                                    

While specific embodiments of the invention have been described, itshould be apparent to those skilled in the art that variousmodifications thereof can be made without departing from the true spiritand scope of the invention. Accordingly, it is intended that thefollowing claims cover all such modifications within the full inventiveconcept.

What is claimed is:
 1. A printed circuit comprising oxidation resistant, electrolessly-deposited copper circuitry on a flexible film substrate wherein said copper is deposited on a activated ink coating prepared by heating a wet ink comprising a polymer and a Group 1B or 8 compound which is adapted to drying at room temperature to a catalytically inert ink.
 2. A printed circuit according to claim 1 wherein said polymer is polyvinylchloride, polyvinylalcohol or a butadiene polymer and said compound is a palladium compound.
 3. A printed circuit comprising oxidation resistant, electrolessly-deposited copper circuitry on a flexible film substrate wherein said copper is deposited on selectively catalytic areas of a catalytically inert coating of a polymer and a Group 1B or 8 compound, wherein said areas are selectively activated.
 4. A printed circuit according to claim 3 wherein said polymer is polyvinylchloride, polyvinylalcohol or a butadiene polymer and said compound is a palladium compound.
 5. A printed circuit according to claim 3 wherein said areas are selectively activated by a laser. 